1. Field of the Invention
The present invention relates to a conveyer device, more particularly, to a conveyer device using a plurality of rollers each incorporating a motor as drive source. In addition, the invention also relates to structure of the connection of rollers each incorporating a drive motor.
2. Description of the Related Art
Pulleys of any conventional belt-conveyer unit and rollers of any conventional roller-conveyer unit are respectively driven by a plurality of motors secured to frames. However, in response to industrial demand for easier assembly work and minimizing cubic space occupied by conveyer installations, recently, a greater number of drive pulleys and drive rollers each incorporating a motor have been introduced.
The term "roller incorporating a motor" designates such a roller internally being equipped with a drive motor which rotatably drives the roller itself such as the one typically disclosed in the Japanese Laid-Open Patent Application Publication No. SHO63-235207 (1988) and the Japanese Laid-Open Patent Application Publication No. HEI4-243720 (1992) for example.
Taking a conventional roller conveyer for example, a plurality of rollers each incorporating a motor are secured to frames as basic structure of such a conventional conveyer unit using plural rollers incorporating motors.
Those motor-incorporated rollers used for any conventional roller conveyer by way of being secured to frames respectively incorporate motors each having rated voltage exactly matching supply voltage conventionally being available.
Those motor-incorporated rollers used for such a conventional roller conveyer respectively incorporate a motor having connection to the power source in parallel.
In terms of supply voltage, normally, 200VAC is commercially available for three-phase alternating current in Japan. Nevertheless, in some cases, 400VAC is also introduced as factory powersource. On the other hand, not only 400VAC, but, in many cases, more than 400VAC of supply voltages are also conventionally used in the U.S.A. and European countries. In other words, there are a wide variety of motor-incorporated rollers using a variety of rated voltages in the world. In consequence, in spite of identical diameter and length, many of those conventional motor-incorporated rollers are devoid of interchangeability.
As a result, users and dealers of conveyer units are obliged to constantly hold a wide variety of motor-incorporated rollers to prepare for repairing those conveyer units.
Furthermore, such a conventional conveyer unit using motor-incorporated rollers has critical problem in that difficulty involves in the use of high-voltage power source.
This is because those rollers incorporating motors are generally inappropriate to use high-voltage power source. In other words, in order to gain impedance compatible with actual voltage while rotating a built-in motor with high voltage, it is imperative that the number of the winding of coils be increased.
However, since each motor is built in a roller body, there is a certain limit on the external diameter of each coil, and thus, the number of the winding of each coil cannot be increased indefinitely.
Although there is an idea to contract wire diameter of each coil in order to solely increase the number of winding of each coil while maintaining external diameter of each coil constant, this in turn significantly lowers mechanical strength of each coil to result in occurrence of potential problem such as disconnection and faulty insulation.